A cohort of anti-HIV positive donors and controls has been under prospective follow-up since 1985. The original analysis of the study was published in the New England Journal of Medicine (321:917, 1989). A reanalysis of the data, 9 years after study initiation is in progress. At enrollment, 182 subjects were Western blot (WB) positive, including 158 asymptomatic donors, nine sexual partners of these donors and 15 persons infected by blood transfusion. In addition, we enrolled a control population consisting of 70 donors who were anti-HIV reactive on the screening enzyme immunoassay (EIA), but WB negative or WB indeterminate (21). Of the 182 participants who were Western blot positive, 87% were donors, 5% sexual partners, and 8% recipients. Of the WB positives, 72 (40%) have AIDS of whom 34 (74%) have died. The death rate could be higher in that some AIDS cases are-lost to follow-up. The remaining 110 (60%) of the WB+ have not to our knowledge developed AIDS, but 60 are lost to follow. Forty-six AIDS-free patients remain in active follow-up and can be studied regarding factors that favor long-term survival in HIV infection. AIDS or HIV-related phenomena have not developed in any of 21 WB indeterminate or WB negative subjects.